Have both short term and long term plans. You’ve had some great suggestions above for short(er) term actions you can take. I would also consider reaching out to other coaches - my younger brother’s XC team was always a mix of serious runners, and a handful of basketball players, lacrosse players, rowers and wrestlers. For kids who need conditioning/to stay in shape and prefer a team activity, group runs can be appealing (one of his friends - a wrestler - would joke he just came for the post-run popsicles. Whatever it takes!).
For the long term: most popular sports start with rec leagues in early elementary school, and many kids are involved because there was a community culture around that sport and their parents pushed it. One of the more successful running programs in our area started building a similar approach probably 20 years ago or so - school-break camps, summer clinics, a family running program on Saturdays that welcomed all ages and levels, themed fun runs throughout the year (Reindeer Race, Bunny Hop, Spooky Run, etc). I have been told that they’ve basically created a farm system and built community interest and support in running, and have seen this pay off.